mention hardware/simulation options in Devices page (#3455)
mention hardware/simulation options in Devices page (#3455)

Mention hardware/simulation options in Devices page.

Should come after #3449. 
balopat/Cirq,quantumlib/Cirq,balopat/Cirq,quantumlib/Cirq,quantumlib/Cirq,quantumlib/Cirq,balopat/Cirq,quantumlib/Cirq